title: Platelet antibody detection by flow cytometry: an effective method to evaluate and give transfusional support in platelet refractoriness.
abstract: BACKGROUND
  Immune platelet refractoriness is mainly caused by human leukocyte antigen antibodies (80-90% of cases) and, to a lesser extent, by human platelet antigen antibodies. Refractoriness can be diagnosed by laboratory tests and patients should receive compatible platelet transfusions. A fast, effective and low cost antibody-screening method which detects platelet human leukocyte/platelet antigen antibodies is essential in the management of immune platelet refractoriness.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the efficiency of the flow cytometry platelet immunofluorescence test to screen for immune platelet refractoriness.
  
  
  METHODS
  A group of prospective hematologic patients with clinically suspected platelet refractoriness treated in a referral center in Campinas, SP during July 2006 and July 2011 was enrolled in this study. Platelet antibodies were screened using the flow cytometry platelet immunofluorescence test. Anti-human leukocyte antigen antibodies were detected by commercially available methods. The sensitivity, specificity and predictive values of the immunofluorescence test were determined taking into account that the majority of antiplatelet antibodies presented human leukocyte antigen specificity.
  
  
  RESULTS
  Seventy-six samples from 32 female and 38 male patients with a median age of 43.5 years (range: 5-84 years) were analyzed. The sensitivity of the test was 86.11% and specificity 75.00% with a positive predictive value of 75.61% and a negative predictive value of 85.71%. The accuracy of the method was 80.26%.
  
  
  CONCLUSIONS
  This study shows that the flow cytometry platelet immunofluorescence test has a high correlation with the anti-human leukocyte antigen antibodies. Despite a few limitations, the method seems to be efficient, fast and feasible as the initial screening for platelet antibody detection and a useful tool to crossmatch platelets for the transfusional support of patients with immune platelet refractoriness.
authors.affiliation: Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Carolina Bonet
authors.initials: CB
authors.lastname: Bub
authors.forename: Beatriz Moraes
authors.initials: BM
authors.lastname: Martinelli
authors.forename: Thayná Mendonça
authors.initials: TM
authors.lastname: Avelino
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Gonçalez
authors.forename: Maria de Lourdes
authors.initials: Mde L
authors.lastname: Barjas-Castro
authors.forename: Vagner
authors.initials: V
authors.lastname: Castro
keywords: Antigens, human leukocyte; Antigens, human platelet; Blood platelets; Flow cytometry; Histocompatibility